467
Federal Aviation Administration, DOT
§ 25.865
(ii) Keep the heater off until re-
started by the crew.
(3) There must be means to warn the
crew when any heater whose heat out-
put is essential for safe operation has
been shut off by the automatic means
prescribed in paragraph (e)(1) of this
section.
(f)
Air intakes. Each combustion and
ventilating air intake must be located
so that no flammable fluids or vapors
can enter the heater system under any
operating condition—
(1) During normal operation; or
(2) As a result of the malfunctioning
of any other component.
(g)
Heater exhaust. Heater exhaust
systems must meet the provisions of
§§ 25.1121 and 25.1123. In addition, there
must be provisions in the design of the
heater exhaust system to safely expel
the products of combustion to prevent
the occurrence of—
(1) Fuel leakage from the exhaust to
surrounding compartments;
(2) Exhaust gas impingement on sur-
rounding equipment or structure;
(3) Ignition of flammable fluids by
the exhaust, if the exhaust is in a com-
partment containing flammable fluid
lines; and
(4) Restriction by the exhaust of the
prompt relief of backfires that, if so re-
stricted, could cause heater failure.
(h)
Heater fuel systems. Each heater
fuel system must meet each power-
plant fuel system requirement affect-
ing safe heater operation. Each heater
fuel system component within the ven-
tilating airstream must be protected
by shrouds so that no leakage from
those components can enter the ven-
tilating airstream.
(i)
Drains. There must be means to
safely drain fuel that might accumu-
late within the combustion chamber or
the heat exchanger. In addition—
(1) Each part of any drain that oper-
ates at high temperatures must be pro-
tected in the same manner as heater
exhausts; and
(2) Each drain must be protected
from hazardous ice accumulation under
any operating condition.
[Doc. No. 5066, 29 FR 18291, Dec. 24 1964, as
amended by Amdt. 25–11, 32 FR 6912, May 5,
1967; Amdt. 25–23, 35 FR 5676, Apr. 8, 1970]
§ 25.863
Flammable fluid fire protec-
tion.
(a) In each area where flammable
fluids or vapors might escape by leak-
age of a fluid system, there must be
means to minimize the probability of
ignition of the fluids and vapors, and
the resultant hazards if ignition does
occur.
(b) Compliance with paragraph (a) of
this section must be shown by analysis
or tests, and the following factors must
be considered:
(1) Possible sources and paths of fluid
leakage, and means of detecting leak-
age.
(2) Flammability characteristics of
fluids, including effects of any combus-
tible or absorbing materials.
(3) Possible ignition sources, includ-
ing electrical faults, overheating of
equipment, and malfunctioning of pro-
tective devices.
(4) Means available for controlling or
extinguishing a fire, such as stopping
flow of fluids, shutting down equip-
ment, fireproof containment, or use of
extinguishing agents.
(5) Ability of airplane components
that are critical to safety of flight to
withstand fire and heat.
(c) If action by the flight crew is re-
quired to prevent or counteract a fluid
fire (e.g., equipment shutdown or actu-
ation of a fire extinguisher) quick act-
ing means must be provided to alert
the crew.
(d) Each area where flammable fluids
or vapors might escape by leakage of a
fluid system must be identified and de-
fined.
[Amdt. 25–23, 35 FR 5676, Apr. 8, 1970, as
amended by Amdt. 25–46, 43 FR 50597, Oct. 30,
1978]
§ 25.865
Fire protection of flight con-
trols, engine mounts, and other
flight structure.
Essential flight controls, engine
mounts, and other flight structures lo-
cated in designated fire zones or in ad-
jacent areas which would be subjected
to the effects of fire in the fire zone
must be constructed of fireproof mate-
rial or shielded so that they are capa-
ble of withstanding the effects of fire.
[Amdt. 25–23, 35 FR 5676, Apr. 8, 1970]
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